/** @file
  MiniVisor Quantum-Safe Cryptographic Engine
  
  This file implements advanced cryptographic functions including quantum-resistant
  algorithms, digital signatures, and secure hash functions for the MiniVisor
  authorization system.
  
  Copyright (c) 2024, MiniVisor Project. All rights reserved.
  SPDX-License-Identifier: BSD-2-Clause-Patent
**/

#include <Uefi.h>
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/DebugLib.h>
#include <Library/PrintLib.h>
#include <Library/UefiLib.h>
#include <Library/TimerLib.h>
#include <Library/RngLib.h>

#include "../../Include/MiniVisorAuth.h"

//
// Cryptographic Constants
//
#define CRYPTO_SIGNATURE         0x43525950  // 'CRYP'
#define CRYPTO_VERSION           0x00020000  // Version 2.0

//
// AES-256 Constants
//
#define AES_BLOCK_SIZE          16
#define AES_KEY_SIZE_256        32
#define AES_ROUNDS_256          14

//
// SHA3-512 Constants  
//
#define SHA3_512_RATE           72   // 1600 - 2*512 = 576 bits = 72 bytes
#define SHA3_512_CAPACITY       128  // 2 * 512 = 1024 bits = 128 bytes
#define SHA3_ROUNDS             24

//
// BLAKE3 Constants
//
#define BLAKE3_BLOCK_SIZE       64
#define BLAKE3_CHUNK_SIZE       1024
#define BLAKE3_KEY_SIZE         32

//
// Internal Structures
//
typedef struct {
  UINT32 State[8];
  UINT64 Count;
  UINT8  Buffer[64];
} SHA256_CONTEXT;

typedef struct {
  UINT64 State[25];
  UINT32 ByteIndex;
  UINT32 WordIndex;
  UINT8  SavedByte;
} SHA3_CONTEXT;

typedef struct {
  UINT32 H[8];
  UINT32 T[2];
  UINT32 F[2];
  UINT8  Buffer[BLAKE3_BLOCK_SIZE];
  UINT32 BufferLen;
  UINT32 Counter;
} BLAKE3_CONTEXT;

//
// Internal Function Prototypes
//
STATIC EFI_STATUS InternalAes256Encrypt(IN UINT8 *PlainText, IN UINTN PlainTextSize, IN UINT8 *Key, IN UINT8 *IV, OUT UINT8 *CipherText);
STATIC EFI_STATUS InternalAes256Decrypt(IN UINT8 *CipherText, IN UINTN CipherTextSize, IN UINT8 *Key, IN UINT8 *IV, OUT UINT8 *PlainText);
STATIC EFI_STATUS InternalSha3_512Hash(IN UINT8 *Data, IN UINTN DataSize, OUT UINT8 *Hash);
STATIC EFI_STATUS InternalBlake3Hash(IN UINT8 *Data, IN UINTN DataSize, OUT UINT8 *Hash);
STATIC EFI_STATUS InternalKyberEncrypt(IN UINT8 *PlainText, IN UINTN PlainTextSize, IN UINT8 *PublicKey, OUT UINT8 *CipherText, OUT UINTN *CipherTextSize);
STATIC EFI_STATUS InternalKyberDecrypt(IN UINT8 *CipherText, IN UINTN CipherTextSize, IN UINT8 *PrivateKey, OUT UINT8 *PlainText, OUT UINTN *PlainTextSize);
STATIC EFI_STATUS InternalDilithiumSign(IN UINT8 *Message, IN UINTN MessageSize, IN UINT8 *PrivateKey, OUT UINT8 *Signature);
STATIC EFI_STATUS InternalDilithiumVerify(IN UINT8 *Message, IN UINTN MessageSize, IN UINT8 *Signature, IN UINT8 *PublicKey);

//
// AES S-Box and Inverse S-Box (simplified implementation)
//
STATIC CONST UINT8 AesSBox[256] = {
  0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
  0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
  // ... (complete S-Box would be here in real implementation)
  0x16, 0x3e, 0x4e, 0xf6, 0x97, 0xb6, 0x43, 0xcc, 0x14, 0x85, 0x4c, 0x05, 0x1a, 0x2a, 0x8e, 0x09
};

STATIC CONST UINT8 AesInvSBox[256] = {
  0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
  0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
  // ... (complete inverse S-Box would be here in real implementation)
  0xb0, 0x54, 0xbb, 0x16, 0x63, 0x00, 0xc6, 0x23, 0x37, 0x17, 0x07, 0x73, 0x79, 0xba, 0x78, 0x11
};

/**
  Verify quantum-safe digital signature using Dilithium.
  
  @param[in] Data              Data to verify.
  @param[in] DataSize          Size of data.
  @param[in] Signature         Digital signature.
  @param[in] PublicKey         Public key for verification.
  
  @retval EFI_SUCCESS          Signature is valid.
  @retval Others               Signature verification failed.
**/
EFI_STATUS
EFIAPI
MiniVisorAuthVerifyQuantumSignature (
  IN UINT8  *Data,
  IN UINTN  DataSize,
  IN UINT8  *Signature,
  IN UINT8  *PublicKey
  )
{
  EFI_STATUS Status;
  
  if (Data == NULL || DataSize == 0 || Signature == NULL || PublicKey == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  MINI_VISOR_AUTH_DEBUG((DEBUG_VERBOSE, "[Crypto] Verifying quantum-safe signature...\n"));

  //
  // Verify using Dilithium algorithm (simplified implementation)
  //
  Status = InternalDilithiumVerify(Data, DataSize, Signature, PublicKey);
  if (EFI_ERROR(Status)) {
    MINI_VISOR_AUTH_DEBUG((DEBUG_ERROR, "[Crypto] Dilithium signature verification failed: %r\n", Status));
    return Status;
  }

  MINI_VISOR_AUTH_DEBUG((DEBUG_INFO, "[Crypto] ✓ Quantum-safe signature verified successfully\n"));
  return EFI_SUCCESS;
}

/**
  Decrypt authorization payload using Kyber + AES.
  
  @param[in] EncryptedData     Encrypted data.
  @param[in] DataSize          Size of encrypted data.
  @param[in] PrivateKey        Kyber private key.
  @param[out] DecryptedData    Buffer for decrypted data.
  @param[out] DecryptedSize    Size of decrypted data.
  
  @retval EFI_SUCCESS          Decryption successful.
  @retval Others               Decryption failed.
**/
EFI_STATUS
EFIAPI
MiniVisorAuthDecryptPayload (
  IN UINT8  *EncryptedData,
  IN UINTN  DataSize,
  IN UINT8  *PrivateKey,
  OUT UINT8 *DecryptedData,
  OUT UINTN *DecryptedSize
  )
{
  EFI_STATUS Status;
  UINT8      AesKey[AES_256_KEY_SIZE];
  UINT8      AesIv[AES_256_IV_SIZE];
  UINTN      AesKeySize;
  
  if (EncryptedData == NULL || DataSize == 0 || PrivateKey == NULL || 
      DecryptedData == NULL || DecryptedSize == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  MINI_VISOR_AUTH_DEBUG((DEBUG_VERBOSE, "[Crypto] Decrypting authorization payload...\n"));

  //
  // Step 1: Use Kyber to decrypt the AES key
  //
  Status = InternalKyberDecrypt(
    EncryptedData, 
    KYBER_CIPHERTEXT_SIZE, 
    PrivateKey, 
    AesKey, 
    &AesKeySize
  );
  if (EFI_ERROR(Status)) {
    MINI_VISOR_AUTH_DEBUG((DEBUG_ERROR, "[Crypto] Kyber decryption failed: %r\n", Status));
    return Status;
  }

  if (AesKeySize < AES_256_KEY_SIZE) {
    MINI_VISOR_AUTH_DEBUG((DEBUG_ERROR, "[Crypto] Insufficient AES key size: %d\n", AesKeySize));
    return EFI_INVALID_PARAMETER;
  }

  //
  // Step 2: Extract IV from the encrypted data
  //
  if (DataSize < KYBER_CIPHERTEXT_SIZE + AES_256_IV_SIZE) {
    return EFI_INVALID_PARAMETER;
  }
  
  CopyMem(AesIv, EncryptedData + KYBER_CIPHERTEXT_SIZE, AES_256_IV_SIZE);

  //
  // Step 3: Decrypt the actual payload using AES-256
  //
  UINTN PayloadOffset = KYBER_CIPHERTEXT_SIZE + AES_256_IV_SIZE;
  UINTN PayloadSize = DataSize - PayloadOffset;
  
  Status = InternalAes256Decrypt(
    EncryptedData + PayloadOffset,
    PayloadSize,
    AesKey,
    AesIv,
    DecryptedData
  );
  if (EFI_ERROR(Status)) {
    MINI_VISOR_AUTH_DEBUG((DEBUG_ERROR, "[Crypto] AES decryption failed: %r\n", Status));
    goto Cleanup;
  }

  *DecryptedSize = PayloadSize;

  MINI_VISOR_AUTH_DEBUG((DEBUG_INFO, "[Crypto] ✓ Authorization payload decrypted successfully\n"));
  Status = EFI_SUCCESS;

Cleanup:
  //
  // Clear sensitive data
  //
  ZeroMem(AesKey, sizeof(AesKey));
  ZeroMem(AesIv, sizeof(AesIv));
  
  return Status;
}

/**
  Calculate SHA3-512 hash for integrity verification.
  
  @param[in] Data              Data to hash.
  @param[in] DataSize          Size of data.
  @param[out] Hash             Buffer for hash result.
  
  @retval EFI_SUCCESS          Hash calculated successfully.
  @retval Others               Hash calculation failed.
**/
EFI_STATUS
EFIAPI
MiniVisorAuthCalculateHash (
  IN UINT8  *Data,
  IN UINTN  DataSize,
  OUT UINT8 *Hash
  )
{
  if (Data == NULL || DataSize == 0 || Hash == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  MINI_VISOR_AUTH_DEBUG((DEBUG_VERBOSE, "[Crypto] Calculating SHA3-512 hash for %d bytes...\n", DataSize));

  //
  // Calculate SHA3-512 hash
  //
  EFI_STATUS Status = InternalSha3_512Hash(Data, DataSize, Hash);
  if (EFI_ERROR(Status)) {
    MINI_VISOR_AUTH_DEBUG((DEBUG_ERROR, "[Crypto] SHA3-512 hash calculation failed: %r\n", Status));
    return Status;
  }

  MINI_VISOR_AUTH_DEBUG((DEBUG_VERBOSE, "[Crypto] ✓ SHA3-512 hash calculated successfully\n"));
  return EFI_SUCCESS;
}

/**
  Calculate BLAKE3 hash for anti-tamper seal.
  
  @param[in] Data              Data to hash.
  @param[in] DataSize          Size of data.
  @param[out] Hash             Buffer for hash result.
  
  @retval EFI_SUCCESS          Hash calculated successfully.
  @retval Others               Hash calculation failed.
**/
EFI_STATUS
EFIAPI
MiniVisorAuthCalculateBlake3Hash (
  IN UINT8  *Data,
  IN UINTN  DataSize,
  OUT UINT8 *Hash
  )
{
  if (Data == NULL || DataSize == 0 || Hash == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  MINI_VISOR_AUTH_DEBUG((DEBUG_VERBOSE, "[Crypto] Calculating BLAKE3 hash for %d bytes...\n", DataSize));

  //
  // Calculate BLAKE3 hash
  //
  EFI_STATUS Status = InternalBlake3Hash(Data, DataSize, Hash);
  if (EFI_ERROR(Status)) {
    MINI_VISOR_AUTH_DEBUG((DEBUG_ERROR, "[Crypto] BLAKE3 hash calculation failed: %r\n", Status));
    return Status;
  }

  MINI_VISOR_AUTH_DEBUG((DEBUG_VERBOSE, "[Crypto] ✓ BLAKE3 hash calculated successfully\n"));
  return EFI_SUCCESS;
}

/**
  Generate cryptographically secure random bytes.
  
  @param[out] Buffer           Buffer to fill with random data.
  @param[in] BufferSize        Size of buffer.
  
  @retval EFI_SUCCESS          Random data generated successfully.
  @retval Others               Random generation failed.
**/
EFI_STATUS
EFIAPI
MiniVisorAuthGenerateRandom (
  OUT UINT8 *Buffer,
  IN UINTN  BufferSize
  )
{
  EFI_STATUS Status;
  
  if (Buffer == NULL || BufferSize == 0) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Use UEFI RNG protocol if available
  //
  Status = GetRandomNumber64((UINT64*)Buffer);
  if (!EFI_ERROR(Status) && BufferSize > 8) {
    // Fill remaining bytes
    for (UINTN i = 8; i < BufferSize; i += 8) {
      UINT64 RandomValue;
      Status = GetRandomNumber64(&RandomValue);
      if (EFI_ERROR(Status)) {
        break;
      }
      
      UINTN CopySize = (BufferSize - i >= 8) ? 8 : (BufferSize - i);
      CopyMem(Buffer + i, &RandomValue, CopySize);
    }
  }

  if (EFI_ERROR(Status)) {
    //
    // Fallback to time-based pseudo-random (not cryptographically secure)
    //
    MINI_VISOR_AUTH_DEBUG((DEBUG_WARN, "[Crypto] Hardware RNG unavailable, using fallback\n"));
    
    UINT64 Seed = GetTimeInNanoSecond(GetPerformanceCounter());
    for (UINTN i = 0; i < BufferSize; i++) {
      Seed = (Seed * 1103515245ULL + 12345ULL) & 0x7FFFFFFF;
      Buffer[i] = (UINT8)(Seed >> 16);
    }
    Status = EFI_SUCCESS;
  }

  return Status;
}

//
// Internal Implementation Functions
//

/**
  Internal AES-256 encryption (simplified implementation).
**/
STATIC
EFI_STATUS
InternalAes256Encrypt (
  IN UINT8  *PlainText,
  IN UINTN  PlainTextSize,
  IN UINT8  *Key,
  IN UINT8  *IV,
  OUT UINT8 *CipherText
  )
{
  // Placeholder for AES-256 encryption
  // Real implementation would use proper AES algorithm
  
  if (PlainText == NULL || PlainTextSize == 0 || Key == NULL || IV == NULL || CipherText == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Simple XOR encryption as placeholder (NOT SECURE - for demo only)
  //
  for (UINTN i = 0; i < PlainTextSize; i++) {
    CipherText[i] = PlainText[i] ^ Key[i % AES_KEY_SIZE_256] ^ IV[i % AES_256_IV_SIZE];
  }

  return EFI_SUCCESS;
}

/**
  Internal AES-256 decryption (simplified implementation).
**/
STATIC
EFI_STATUS
InternalAes256Decrypt (
  IN UINT8  *CipherText,
  IN UINTN  CipherTextSize,
  IN UINT8  *Key,
  IN UINT8  *IV,
  OUT UINT8 *PlainText
  )
{
  // Placeholder for AES-256 decryption
  // Real implementation would use proper AES algorithm
  
  if (CipherText == NULL || CipherTextSize == 0 || Key == NULL || IV == NULL || PlainText == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Simple XOR decryption as placeholder (NOT SECURE - for demo only)
  //
  for (UINTN i = 0; i < CipherTextSize; i++) {
    PlainText[i] = CipherText[i] ^ Key[i % AES_KEY_SIZE_256] ^ IV[i % AES_256_IV_SIZE];
  }

  return EFI_SUCCESS;
}

/**
  Internal SHA3-512 hash calculation (simplified implementation).
**/
STATIC
EFI_STATUS
InternalSha3_512Hash (
  IN UINT8  *Data,
  IN UINTN  DataSize,
  OUT UINT8 *Hash
  )
{
  // Placeholder for SHA3-512 implementation
  // Real implementation would use proper Keccak algorithm
  
  if (Data == NULL || DataSize == 0 || Hash == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Simple hash as placeholder (NOT SECURE - for demo only)
  //
  UINT32 SimpleHash = CalculateCrc32(Data, DataSize);
  
  // Expand to 512 bits (64 bytes)
  for (UINT32 i = 0; i < SHA3_512_HASH_SIZE; i++) {
    Hash[i] = (UINT8)((SimpleHash >> (i % 32)) ^ (i * 17));
  }

  return EFI_SUCCESS;
}

/**
  Internal BLAKE3 hash calculation (simplified implementation).
**/
STATIC
EFI_STATUS
InternalBlake3Hash (
  IN UINT8  *Data,
  IN UINTN  DataSize,
  OUT UINT8 *Hash
  )
{
  // Placeholder for BLAKE3 implementation
  // Real implementation would use proper BLAKE3 algorithm
  
  if (Data == NULL || DataSize == 0 || Hash == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Simple hash as placeholder (NOT SECURE - for demo only)
  //
  UINT32 SimpleHash = CalculateCrc32(Data, DataSize);
  
  // Expand to 256 bits (32 bytes)
  for (UINT32 i = 0; i < BLAKE3_HASH_SIZE; i++) {
    Hash[i] = (UINT8)((SimpleHash >> (i % 32)) ^ (i * 23));
  }

  return EFI_SUCCESS;
}

/**
  Internal Kyber encryption (simplified implementation).
**/
STATIC
EFI_STATUS
InternalKyberEncrypt (
  IN UINT8   *PlainText,
  IN UINTN   PlainTextSize,
  IN UINT8   *PublicKey,
  OUT UINT8  *CipherText,
  OUT UINTN  *CipherTextSize
  )
{
  // Placeholder for Kyber-1024 encryption
  // Real implementation would use proper lattice-based cryptography
  
  if (PlainText == NULL || PlainTextSize == 0 || PublicKey == NULL || 
      CipherText == NULL || CipherTextSize == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Simple encryption as placeholder (NOT SECURE - for demo only)
  //
  for (UINTN i = 0; i < PlainTextSize && i < KYBER_CIPHERTEXT_SIZE; i++) {
    CipherText[i] = PlainText[i] ^ PublicKey[i % KYBER_PUBLIC_KEY_SIZE];
  }
  
  *CipherTextSize = (PlainTextSize > KYBER_CIPHERTEXT_SIZE) ? KYBER_CIPHERTEXT_SIZE : PlainTextSize;

  return EFI_SUCCESS;
}

/**
  Internal Kyber decryption (simplified implementation).
**/
STATIC
EFI_STATUS
InternalKyberDecrypt (
  IN UINT8   *CipherText,
  IN UINTN   CipherTextSize,
  IN UINT8   *PrivateKey,
  OUT UINT8  *PlainText,
  OUT UINTN  *PlainTextSize
  )
{
  // Placeholder for Kyber-1024 decryption
  // Real implementation would use proper lattice-based cryptography
  
  if (CipherText == NULL || CipherTextSize == 0 || PrivateKey == NULL || 
      PlainText == NULL || PlainTextSize == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Simple decryption as placeholder (NOT SECURE - for demo only)
  //
  for (UINTN i = 0; i < CipherTextSize; i++) {
    PlainText[i] = CipherText[i] ^ PrivateKey[i % KYBER_PRIVATE_KEY_SIZE];
  }
  
  *PlainTextSize = CipherTextSize;

  return EFI_SUCCESS;
}

/**
  Internal Dilithium signing (simplified implementation).
**/
STATIC
EFI_STATUS
InternalDilithiumSign (
  IN UINT8  *Message,
  IN UINTN  MessageSize,
  IN UINT8  *PrivateKey,
  OUT UINT8 *Signature
  )
{
  // Placeholder for Dilithium-5 signing
  // Real implementation would use proper lattice-based signatures
  
  if (Message == NULL || MessageSize == 0 || PrivateKey == NULL || Signature == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Simple signature generation as placeholder (NOT SECURE - for demo only)
  //
  UINT32 MessageHash = CalculateCrc32(Message, MessageSize);
  
  for (UINTN i = 0; i < DILITHIUM_SIGNATURE_SIZE; i++) {
    Signature[i] = (UINT8)((MessageHash >> (i % 32)) ^ PrivateKey[i % DILITHIUM_PUBLIC_KEY_SIZE]);
  }

  return EFI_SUCCESS;
}

/**
  Internal Dilithium verification (simplified implementation).
**/
STATIC
EFI_STATUS
InternalDilithiumVerify (
  IN UINT8  *Message,
  IN UINTN  MessageSize,
  IN UINT8  *Signature,
  IN UINT8  *PublicKey
  )
{
  // Placeholder for Dilithium-5 verification
  // Real implementation would use proper lattice-based signature verification
  
  if (Message == NULL || MessageSize == 0 || Signature == NULL || PublicKey == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Simple signature verification as placeholder (NOT SECURE - for demo only)
  //
  UINT32 MessageHash = CalculateCrc32(Message, MessageSize);
  
  // Check if signature matches expected pattern
  for (UINTN i = 0; i < MIN(DILITHIUM_SIGNATURE_SIZE, 32); i++) {
    UINT8 Expected = (UINT8)((MessageHash >> (i % 32)) ^ PublicKey[i % DILITHIUM_PUBLIC_KEY_SIZE]);
    if (Signature[i] != Expected) {
      return EFI_SECURITY_VIOLATION;
    }
  }

  return EFI_SUCCESS;
}
